Polymerization of 1, 3-dienes in the presence of beta-unsaturated aliphatic iodides



Patented Aug; 15, 1950 POLYMERIZATION OF IJ-DIENES IN THE PRESENCE OFBETA-UNSATURATED ALI- PHATIC IODIDES George w. Scott, Wilmington, Del,minor to du Pont de Nemo uradv Company, Wilmington, Del., a corporationof Delaware No Drawing. Application May 28, 1948, Serial No. 871,914

11 Claims. (01. zso oz.:)

This invention relates to an improved method of modifying thepolymerization of 1,3-dienes and interpolymerization of the same withmonoolefinic polymerizable compounds, and to new and improved polymersproduced thereby.

In the polymerization of 1,3-dienes in the absence of modifying agents,polymers are obtained normally which are tough and dry and which aretherefore difficult or impossible to handle in the usual types of rubberprocessingmachinery. Modifying agents are therefore usually employed togive polymers which are soft and which are readily processable or whichcan be made soft and readily processable by mechanical working or by theaddition of small amounts of peptizing agents (chemical softeners). Thecommonly used modifying agents are sulfur, or sulfur-containingsubstances such as mercaptans, which are employed usually in amounts upto 2% of the weight of the polymers. In addition to its modifyingeffect, sulfur, when present during the polymerization, particularly ofchloroprene, improves the physical properties of films of the polymersdeposited directly from their aqueous dispersions. In general, theimproved plasticity of the synthetic rubbers of the 1,3-diene'types isobtained by the addition of reagents which ordinarily retardpolymerization, such as sulfur or sulfur compounds, and therefore it hasbeen necessary to employ with these modifying agents catalysts oraccelerators which increase the rate of polymerization.

Sulfur and sulfur-containing compounds often I render syntheticelastomers unsuitable for certain uses because of the presence of thesulfur in the finished elastomer, and usually they impart to theelastomer an odor which, in many. cases, is undesirable. It is thereforedesirable that modifiers for 1,3-diene-type elastomers be produced whichdo not impart to the synthetic elastomers the objectionable propertiesimparted thereto by the sulfur or sulfur-containing compounds and whichare free from the metal compounds often required to effectpolymerization when sulfur or sulfur compounds are used as modifyingagents.

It is therefore an object of this invention to provide a method formodifying the polymerization and interpolymerization of 1,3-dienes whichwill not introduce sulfur into the resulting polymer, making possiblethe production of sulfurfree elastomers. It is a further object of theinvcntion to provide a process for producing chloroprene and butadienepolymers which have improved storage stability, flatter curlng range andbetter resistance to heat aging, and to cut 2 growth, than are normallyobtained by the use of sulfur modifying agents. It is a further objectof the invention to provide a process for the polymerization of1,3-dienes which will permit a more rapid polymerization than whensulfur or sulfur-containing compounds are employed, thereby resulting inincreased production and/or decrease in the amount of polymerizationcatalyst needed to carry out the process. A still further object is toprovide a process for producing polymers of 1,3-dienes which haveimproved working propertles and which result in more stable laticesbecause of the lower concentration of electrolytes present therein, andone which produces polymers of 1,3-.dienes free from the objectionableodor associated with sulfur compounds. Another to provide a method ofmodifying the polymerization and interpolymerization of 1,3-dienes withagents which, when used in only relatively small amounts, give plasticpolymers particularly suitable for use in cements of low viscosity andhigh solids content.

I have found that the objects as above set forth can be accomplished bycarrying out the polymerization of 1,3-dienes, such as 1,3-butadiene and2-chloro-1,3-butadiene, or the interpolymerization of"these dienes witheach other or with mono-oleflnic polymerizable materials in the presenceof small amounts of aliphatic iodo compounds which contain the nucleus:

which compounds contain not more than 8 carbon atoms in the aliphaticchain and which are straight chain aliphatic compounds. As illustrativeof the class of compounds which I have found useful in carrying out thisinvention, are 1-iodopropene-2 (allyl iodide), 1-iodopentene-2,2-iodobutene-3, 3-iodopentene-4, l-iodohexadime-2,4,1-iodoheptadiene-2,4, 1-iodo-3-chlorobutene-2, 1-iodo-2-chlorobutene-2,l-chloro-S- iodobutene-l, 1-iodo-3-chlorohexadlene-2,4, 1,4-diodobutene-2, l-iodoli-bromobutene-Z. This class of compounds may bereferred to generally as monoand di-halogen substituted straight chainunsaturated aliphatic compounds selected from the group consisting ofthe mono-oleflne and di-oleflne series containing not more than 8 carbonatoms and having the nucleus object of the invention is i 3 in whicheach carbon atom carries no more than one halogen atom. The preferredgroup of compounds within the class are those which contain the primaryiodide group --CH2-I. 1-iodo-3- chlorobutene-2 is esneciallvnreferred.

The 1-iodo-3-chlorobutene-2 mentioned above the invention. The partsused are by weight, un-

less otherwise specified.

v Example 1 chloroprene was polymerized in an emulsion at 40 0., usingthe following recipe, the modifying agent and rosin being firstdissolved in the chloroprene, which was then emulsified in the watercontaining the other ingredients.

Parts Chioroprene 100 Water f 147.5 Dispersin'g agent 0.75 Nancy woodrosin 4.0 Sodium hydroxide 0.9 Potassium persulfate 0.6 Modifying agentAs indicated Sodium salt of the reaction product of naphthalene,sulfuric acid and formaldehyde.

. i 4 eifective modifying agents for chloroprene polymerization.

Example 2 A series of polymers was prepared as in Example 1, in order tostudy the effect of concentration of one of these modifying agents,1-iodo- 3-chlorobutene-2, on the degree of modification.

Williams Parts of 1 l-Iodod- Percent Plasticity Recov- Description ofChloro- Yield Number cry Polymer butene-2 0 85 346 184 Tough and dry. 10. 175 88 181 174 Do. 1 0. 175 88. 5 134 79 Well plasticized and goodmilling. 0. 25 84 90 4 Sotfat and silghtly 0. 60 82 Extremely soft andtacky.

1 Only 0.1 part potassium persuiiate used in the emulsion recipe.

1 Only 0.3 part potassium persuliate used in the emulsion recipe.

This example shows that these allylic iodides areefiective at very lowconcentrations for producing substantial modification of chloroprene.with small variations in concentration resulting in polymers of quitedifferent physical properties.

i The soft polymers prepared with the higher concentrations of1-iodo-3-chlorobutene-2 are very effective for producing low viscositycements with high solids content.

7 Example 3 Polymers prepared with allylic iodides as modifying agentsgive vulcanizates which have; hightensile strength and good elongationat break. These polymers are compared to sulfur modified polymer in thefollowing tread stock. The polymers containing the iodides used for thiscomparison were made according to Example 1, except for the use of lessallyl iodide, as shown.

Ind. Eng. Chem. 16, The lower numbers represent the greaterpiasticities. 1 Very poor=tougb polymer which fails to band on a mill.

Good-polymer which iorms a coherent band on the mill, making compoundingpossible Excellentlymer e mill. 7 i The recipe used in preparing thispolymer contained a dehydrogenated resin and 1 .0 part of potassiumpersuliate in place-of the may. wood rosin and 0.6 part of potassiumpersuliate. This example shows that allylic iodides are very which formsa smooth continuous band on 40 In each case, -the polymerization wasstopped Parts when the emulsion reached a specific gravity Polymer v 100of 1.057 to 1.058 by the addition of 2.5 parts-ofPhenylalpha-naphthylamine 2 tetra-ethyl thiuram disulfide dispersed inwater. MPC bla k 36 The emulsion was coagulated by freezing in thinMagnesium oxide 4 layers and the polymer was washed with water, Zincoxide 5 c Mae Saar us 11 a Modifying- Agens m (1b.! sq. in.) (lbs/sq.in.) Per Cent 0.25 part 1-iodo-3-chlorobutene-2 30 min. at 287 F 1, 2204. 000 640 0.25 part Ally] iodide 30min. at 287 F 1, 360 a 4. 150 5900.60 part sum 15 mm. at 287 F 1,140 a, 520 050 dried with warm air, andmilled. The resulting Y Exampl 4 1 data are tabulated W This illustratesthe use of 1-iodo-3-chloro- William I V butene in the polymerization ofchloroprene in M A t Pei-Cent Hams Becovacidic emulsions. Choloroprenewas polymerize mg Yield Mitt? Mmabmty .at 40 C. in the followingemulsion:

' g Parts s5 34a v 10pertaliyliodide-- as 72 aim: 'r :28 mo?2tfmt'* 84 I4 Dizp rsing a ent 2 c g "'flirlii'hd'iiiiii Sodium salt of laurylsulfate 1 2.4. Acetic acid 0.5 fifilii m 87 86 7 Emnmt' Potassiumpersulfate 1,0 Potassium ferricyanide 0.05 1 Based on method describedby Williams h 0.5

1 Sodium salt of a reaction roduct of na hthalene, sulfuric' acid andformaldehyde. p p

The polymerization was stoppedat 86% product yield by the addition of 2parts of a 55% N-phenyl-alpha-naphthylamine-45% diphenylamine mixtureand 0.1 part of phenthiazine. The late; was coagulated with a mixture ofbrine and ethyl alcohol, and the polymer was washed and dried on'a.The-plasticity number was 8'! and the 2; Milling was good,

kzainpleo This illustrates the use of l-iodo-3- chlorobutane-2 in thepolymerization of chlcroprene' to give a modified polychloroprene latex.Chloroprene was polymerized at 40 C. under a nitrogen atmosphere to apolymer yield of 98% in an emulsion prepared as indicated by thefollowing recipe:

Parts Chloroprene 100 Water 100 Nancy wood rosin 4 Sulfur 0.01 Sodiumhydroxide 1.056 Potassium persulfate 0.4 1-iodo-3-chlorobutene-2 0.1

The finished latex was compounded as follows:

Parts Latex 200 Hard clay Zinc oxide 5 Phenyl-beta-naphthylamine 2 A dipfilm was prepared from the compounded latex andcured in air for minutesat 140 C. The 600% modulus (980 lbs. per sq.'-in.) of this cured filmwas much lower than that (1525 lbs. per sq. in.) of a similar fllm'froma latex made in the absence of 1-iodo-3-chlorobutene-2, indieating1-iodo-3-chlorobutene-2 to be an effective modifying agent forpolychloroprene latex.

. Example 6 A polymer of 75% butadiene-l, 3 and styrene was prepared inthe following emulsion,

using l-iodo-3'-chlorobutene-2 as the essential modifying agent.

/ Parts Monomer mixture 100 Water 180 Rubber reserve soap 1 5 Potassiumpersulfate 0.5

Dodecyl mercaptan 0.05

' 1iodo-3-chlorobutene-2 0.36

Sodium salt of mixed long chain saturated and unsaturated aliphaticacids.

Example 7 A mixture of butadiene-l,3 (75%) and acrylo- 6 I thepolymerizable materials with which More incorporated. m the paration ofpolymers a n good milling properties, the amounts to be usedmay-varyfrom 0.10% to 2.0%. Where extremely soft and-plastic polymersare'desired.

or where the resulting polymer is to be used in cements of low viscosityand high soiitk content, as high as 10% of these modifying agents may beused, jbased on the weight of the polymerizable material which they,employed. These modifying agents are effective in both alkaline andacid emulsions and-also when I used alone or when used in combinationwith other modifying agents such as sulfur or mercaptans.

The allylic iodides may be used as modifying agents in any of the usualpolymerization sysms, for example, in sodium and other rosinate emulsionsystems or where the emulsifying agents are ethylene oxide-higheralcohol condemation products or the alkali salts of sulfonated alkylalcohols, of fatty acids, or of aliphatic and aromatic sulfonates. Ifdesired, the polymerization may be accelerated by the use of the usualaccelerator such as potassium persulfate or other soluble persulfate,benzoyl peroxide, hydrogen peroxide, and the like. These allylic iodidesare also effective modifying agents for solution or for massivepolymerization of the 1,3-dienes and mixtures thereof with the otherpolymerizable compounds.

These allylic iodides modify the polymer-imtion of LB-dienss such aschloroprene and 1,3- butadiene, and the interpolymerization of suchdlenes with each other or with mono-oleflnic polymerizable compoundswhich are polymerizable with 1,3-dienes such-as styrene oracrylonitrile, acrylates, alkylacrylates. etc. This invention isparticularly applicable in the polymerization' of 1,3-dienes such aschloroprene, 1,3- butadiene, etc., and in the interpolymerization ofmixtures of the same with each other or in mixtures with mono-oleflnic vpolymerizable compounds where the mixture contains at least oi the1.8-diene.

This invention provides modifying agents which do not contain sulfur,making possible the pronitrile (25%) was polymerized in the same systemas used in Example 6, except that 1.08 parts of 1-iodo-3-chlorobutenewas used as the modifying agent.

The polymer obtained was more plastic and smoother milling than asimilar polymer prepared in the absence of 1-iodo-3-chlorobutene-2.

These allylic iodides are effective modifying agents over a widetemperature range, with the preferred temperatures being between 5 and55 0. They may be employed in amounts varying from 0.10% to 10.0%, basedon the weight of.

duction of sulfur-free elastomers similar to those modified withiodoform. These modifying agents give chloroprene polymers which haveimproved storage stability, flatter curing range and better resistanceto heat aging and to cut growth than su fur modified polymers. Thesemodifying agents allow more rapid polymerization than an equivalentamount of sulfur, resulting in increased production or ina decrease inthe amount of catalyst'necessary. In the case of the production of asynthetic latex, this latter efiect results in a more stable latexbecause of lower concentration of electrolytes. A further advantage isthat the use of these compounds eliminates the odor often associatedwith sulfur compounds, and polymers are produced having good workingproperties.

It is possible with these modifying agents to obtain very plasticpolymers for use in cements of low viscosity and high solids content.

I claim:

1. A method for preparing readily processable rubber-like polymers of1,3-butadiene which comprises carrying out the polymerization of the1,3-butadiene in an aqueous emulsion and in the presence of from 0.10%to 10.0% of 1-iodo-3- chlorobutene-2, based on the weight of the 1,3-butadiene. 1

the polymerization of 2-chlorobutadiene-1,3 in an aqueous emulsion andin the presence of from 0.10% to 10.0% of allyl iodide based on theweight of the 2-chlorobutadiene-1,3.

4. A method for preparing readily processable re-i and contains onlycarbon, hydrogen and halogen of the group consisting of chlorine,bromine and iodine.

8. A method for preparing readily processable rubber-like polymers or1,3-butadiene compounds of the group consisting of2-chloro-l,3-butadiene and 1,3-butadiene which comprises carrying outthe polymerization oi. the monomeric material, which contains at least50% o! the 1,3-butadiene compound, in an aqueous emulsion and in thepoly-chloroprene which comprisescarrying'out the polymerization of2-chlorobutadiene-1,3 in an aqueous emulsion and in the presence of from0.10% to 10.0% of 1,4-diiodobutene-2 based on the weight of the2-ch1orobutadiene-1,3.

5. A method for preparing readily processable rubberlike polymers of1,3-butadiene compounds of the group consisting of2-chloro-1,3-butadiene and 1,3-butadiene which comprises carrying outthe polymerization of the monomeric material, which contains at least50% of the 1,3-butadiene compound, in the presence of from 0.10% to10.0%, based on the-weight of the polymerizable material, of a halogensubstituted straight chain unsaturated aliphatic compound selected fromthe group consisting of the mono-olefine and diolefine series containingnot more than 8 carbon atoms with not more'than two halogen atoms in themolecule and not more than one halogen on a single carbon atom, whichcompound has the nucleus which contains at least 50%'of the1,3-butadiene compound, in the presence of from 0.10% to 10.0%, based onthe weight of the polymerizable material, of a dihalogen straight chaincompound selected from the group consisting of the mono-olefine anddi-oleflne series containing not more than 8 carbon atoms, whichcompound has the nucleus and contains only carbon, hydrogen and halogenof the group'consisting of chlorine, bromine and iodine.

7. A method for preparing readily processable rubber-like polymers of1,3-butadiene compounds of the group consisting of 2-ohloro-l,3-

butadiene and. 1,3-butadiene which comprises carrying out thepolymerization of the monomeric material, which contains at least 50% ofthe 1,3-butadiene compound, in the presence of from 0.10% to 10.0%,based on the weight of the polymerizable material, 01' a halogensubstituted straight chain unsaturated aliphatic compound selected fromthe group consisting of the monoolefine and 'di-oleflne seriescontaining not more than 8 carbon atoms with not more than two halogenatoms in the molecule and not more than one halogen on a single carbonatom, which compound has the nucleus presence of from 0.10% to 10.0%,based on the weight or the 1,3-butadiene compound, of a halogensubstituted straight chain unsaturated aliphatic compound selected fromthe group consisting of the mono-oleflne and di-oleflne seriescontaining not more than 8 carbon atoms with not more than two halogenatoms in the molecule and not more than one halogen on a single carbonatom, which compound has the nucleus and contains only carbon, hydrogenand halogen of the group consisting oi. chlorine, bromine and iodine.

9. A method for preparing a readily processable rubber-like polymer of a1,3-butadiene which comprises carrying out the polymerization of the1,3-butadiene in the presence of from 0.10% to 10.0%, based on theweight of the 1,3-butadiene, of a halogen substituted straight chainunsaturated aliphatic compound selected from the group consisting of themono-olefine and di-olefine series containing not more than 8 carbonatoms with not more than two halogen atoms in the molecule and not morethan one halogen on a single carbon atom, which compound has the nucleusand contains only carbon, hydrogen and halogen of the group consistingof chlorine, bromine and iodine.

10. A method for preparing a readily processable rubber-like polymer ofa 1,3-butadiene which comprises carrying out the polymerization of the1,3-butadiene in an aqueous emulsion and in the presence of from 0.10%to 10.0%, based on the weight of the 1,3-butadiene, of a halogensubstituted straight chain unsaturated aliphatic compound selected fromthe group consisting of the mono-olefine and di-olefine seriescontaining not more than 8 carbon atoms with not more than two halogenatoms in the molecule and not more than one halogen on a single carbonatom, which compound has the nucleus and contains only carbon, hydrogenand halogen of the group consisting of chlorine, bromine and 10 than 8carbon atoms with not more than two REFERENCES CITED halogen atoms inthe molecule and not more than J, one halogen on a single carbon atom,which comy? ig g gg i fg are of record m the pound has the nucleus C C CUNITED STATES PATENTS Hr-I 5 l l Number Name Date and contains onlycarbon, hydrogen and halogen 2. .3 Carothers fl 37 oi the groupconsisting of chlorine, bromine and iodine.

GEORGE W. SCO'I'I. 1

7. A METHOD FOR PREPARING READILY PROCESSABLE RUBBER-LIKE POLYMERS OF1,3-BUTADIENE COMPOUNDS OF THE GROUP CONSISTING OF 2-CHLORO-1,3BUTADIENEAND 1,3-BUTADIENE WHICH COMPRISES CARRYING OUT THE POLYMERIZATION OF THEMONOMERIC MATERIAL, WHICH CONTAINS AT LEAST 50% OF THE 1,3-BUTADIENECOMPOUND, IN THE PRESENCE OF FROM 0.10% TO 10.0%, BASED ON THE WEIGHT OFTHE POLYMERIZABLE MATERIAL, OF A HALOGEN SUBSTITUTED STRAIGHT CHAINUNSATURATED ALIPHATIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF THEMONOOLEFINE AND DI-OLEFINE SERIES CONTAINING NOT MORE THAN 8 CARBONATOMS WITH NOT MORE THAN TWO HALOGEN ATOMS IN THE MOLECULE AND NOT MORETHAN ONE HALOGEN ON A SINGLE CARBON ATOM, WHICH COMPOUND HAS THE NUCLEUS